T1L12 ventricular system Flashcards
ventricular system overview
series of CSF filled interconnected spaces
continuous with the subarachnoid space and central canal
development of ventricles
lumen of neural tube becomes ventricles and central canal
ependymal layer lines ventricles and central canal
- lumen expands at cranial end to form ventricles
lateral ventricles
very large, bilateral
formed of body, posterior horn, anterior horn, inferior horn s6/7
on a scan from above, they are in 4 places as c shaped
borders: septum pellucidum seperates the 2 corpus callosum sits on roof caudate nucleus sits in lateral wall hippocamus sits in floor of inferior horn
interventricular foramen
lateral ventricles communicate with the third ventricle via interventricular foramen
third ventricle
slit like cleft between thalami
inferior and medial to lateral ventricles
borders:
fornix forms roof
big s12
cerebral aqueduct
third communicates with fourth through the cerebral aqueduct
surrounded by midbrain
fourth ventricle
surrounded by hindbrain:
- cerebellum posterior
- pons and medulla anterior
- cerebellar peduncles lateral
rhomboid shape
continuous with the central canal of the spinal chord and the subarachnoid space
s15
communication: 3 foramen enter into subarachnoid space:
2 x foramen of luschka
1 x foramen of magendie
into cisterna magna
s17
choroid plexus
- produces CSF
- filters blood from internal carotid and basilar arteries
- choroid plexus present throughout ventricles
- present throughout ventricles
60% CSF produced in ventricles- other 40% at other sites
structure:
capillary network surrounded by cuboidal epithelium
- blood is filtered through fenestrated capillaries
- components transported through cuboidal epithelium into ventricles s20
tight gap junctions between epithelial cells prevents macromolecules from entering the csf
- blood brain barrier
- permeable to water and CO2
the cuboidal epithelium of the choroid plexus:
- specialised
- villi to increase SA
- active transport to CSF
- bidirectional (uptake metabolites to circulation)
CSF composition
- different ion concs than plasma due to active transport
- very few cells
- ideal for functioning of neurons
CSF circulation flow
lateral ventricles >intraventricular foramen> third ventricle >cerebral aqueduct fourth ventricle >luschka and magendie foramina subarachnoid space
> > 1&2
1) down dorsal spinal subarachnoid space
up ventral spinal subarachnoid space
2) over cerebellum/cerebral hemispheres through subarachnoid space
into superior sagittal sinus via arachnoid granulations
s23/24
subarachnoid space
lies between pia and arachnoid
- follows contours of the brain
functionally important:
CSF in contact with brain parenchyma
- transfer micronutrients into brain and remove metabolites
arachnoid granulation
herniations of arachnoid membrane through dura mater into venous sinuses
- superior sagittal and transverse sinus s26
absorption of CSF
CSF pressure must exceed that in venous sinuses
if venous pressure > CSF pressure, the tips of the villi close off to prevent blood entering CSF
arachnoid villi are a one way valve
CSF volume
500ml per day
total 90-140 ml in system
- excess absorbed via arachnoid granulations
4 main functions of CSF
- hydraulic buffer to cushion brain against trauma
- vehicle for removal of metabolites from CSF
- stable ionic environment for neural function
- transport of neurotransmitters and chemicals
